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C.NETWORKING (CN 121) UE 2021-2022 SOLVED INTERACTIVE

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**Introduction to Computer Networking - Exam

UNIVERSITY OF DODOMA
College of Informatics and Virtual Education
CN 121 – INTRODUCTION TO NETWORKING
Academic Year 2021/2022 END OF SEMESTER EXAMINATION

SECTION A: (15 MARKS)

Answer ALL questions in this section.

Question One

Read each question carefully and choose the most correct response.
(0.5 Marks Each)

i. The shape of the path that data takes through a network is called ______.

  • A. Local area network
  • B. Logical topology
  • C. Vulcan mindset
  • D. Physical topology
  • E. Infrastructure Mode

ii. Satellites commonly use ______ to transmit data.

  • A. Light
  • B. Shortwave radio
  • C. Cables
  • D. Microwaves
  • E. Ethernet technology waves

iii. When a signal on a copper cable loses strength over time as it travels down the wire, it is called

  • A. Crosstalk
  • B. Duplexing
  • C. Attenuation
  • D. Interference
  • E. Latency

iv. A satellite orbit that allows for satellite communications used for GPS networks is called ______.

  • A. Geostationary orbit
  • B. Low Earth orbit
  • C. Medium Earth orbit
  • D. International Space Station
  • E. Mohilya orbit

v. It is dependent on the underlying physical networks.

  • A. MAC address
  • B. IP address
  • C. Host name
  • D. Application specific address
  • E. Port address

vi. Used by a router to send a message to every host on a local network

  • A. Network address
  • B. Loopback address
  • C. Direct broadcast address
  • D. Limited broadcast address
  • E. Broadcast address

vii. Which term best describes a device that is built into a computer’s motherboard that allows that computer to access a network?

  • A. Network Interface
  • B. Network Interface Card
  • C. Bridge
  • D. Bandwidth Shaper
  • E. Switch

viii. What is the hexadecimal equivalent of the Ethernet address 01011010 00010001 10100100 00011000 10101010 00001111?

  • A. 5A:88:A4:18:55:F0
  • B. 5A:81:B8:84:AA:0F
  • C. 5A:18:5A:18:55:F0
  • D. 5A:11:55:18:AA:0F
  • E. 5A:08:A5:18:AA:0F

ix. ______ transmission technology (based on Ethernet) provides a data rate of 1 billion bits per second.

  • A. 10BASE-T Ethernet
  • B. Standard Ethernet
  • C. Fast Ethernet
  • D. Gigabit Ethernet
  • E. 1000BASE-LX

x. Suppose your network is connected to another network via a router. Which OSI model layer provides the information necessary to direct data between the two networks?

  • A. Network layer
  • B. Physical layer
  • C. Data Link layer
  • D. Session layer

Question Two

Match the item in Column A with its corresponding item in Column B.

Column A
i. A short-range wireless digital standard aimed at linking cellphones, computers, and peripherals up to distances of 10m.
ii. Cable that transmits data as pulses of light.
iii. Masquerading as a trustworthy entity in an electronic communication.
iv. A 10Base5 network is also known as
v. Port Address v. Method used to maliciously attempt to compromise network security.
vi. Changes from hop to hop
vii. Malicious program that modifies entries in files of an infected Windows system.
viii. Device that is used to break up a larger LAN into smaller LANs.
ix. An attempt to make a computer resource unavailable to its intended users.

Column B

  • A. Bridge
  • B. Thicknet
  • C. Web URL address
  • D. Trojan horse
  • E. Security mechanics
  • F. Bluetooth
  • G. Denial of service
  • H. Rootkit
  • I. MAC address
  • J. TCP/UDP
  • K. IP address
  • L. Thinnet
  • M. Phishing
  • N. Security attacks
  • O. Fiber optic
  • P. Spoofing

Question Three

a. For each of the services shown below, state whether a simplex, half-duplex or full-duplex form of communication is most suitable.
(0.5 Marks Each)

i. Traditional terrestrial TV

ii. Radio broadcasting

iii. Telephone call

iv. Walkie-talkie

b. Compare STP and UTP cable in terms of cost, throughput, connector and noise immunity.
(1 Mark)

c. Mention the OSI layers responsible for the following tasks:
(0.5 Marks Each)

i. Establishes, maintains, and synchronizes the interactions between communicating devices.

ii. Selecting the best path from the source to the destination station.

iii. Transmit the individual bits from one node to another node.

iv. Provides the network services to the end-users.

SECTION B: (45 MARKS)

Attempt THREE (3) out of FOUR (4) questions provided.

Question Four

(15 Marks)

a. A computer network is to consist of 20 stations. Determine the number of links required if:
(0.5 Marks Each)

i. Mesh topology is used

ii. Star topology is used

iii. Bus topology

b. Suppose that four stations are designated as hubs, each fully interconnected with the others. The remaining 16 stations are equally distributed to the hubs, any one station only being connected to one hub. Sketch the topology and determine the number of links.
(9.5 Marks)

c. Compare all four topologies from (a) and (b).
(4 Marks)

Question Five

(15 Marks)

a. Find the class of the following IP addresses:
(1 Mark Each)

i. 158.223.1.108

ii. 227.13.14.88

b. What is the address space in each of the following systems?
(1 Mark Each)

i. A system with 8-bit addresses

ii. A system with 16-bit addresses

iii. What is the network address if one of the addresses is 167.199.170.82/27?
(2 Marks)

c. Suppose you are employed as an IT administrator at a certain IT company in Dodoma. The company is granted a site address 170.85.0.0 and needs to have 1000 subnets.

i. If n is the total number of subnets required to accommodate your design, what is the value of n?
(1 Mark)

ii. For the value of n in (i) above, find the subnet mask.
(2 Marks)

iii. Find the ranges of addresses for subnet 1 and subnet (n-100).
(3 Marks)

Question Six

(15 Marks)

An ISP is granted a block of addresses starting with 150.80.0.0/16. The ISP wants to distribute these blocks to 2600 customers as follows:

  • 200 medium businesses, each needs 128 addresses
  • 400 small businesses, each needs 16 addresses
  • 2000 households, each needs 4 addresses

a. For each group, design the subblocks and give the slash notation for each subblocks.
(10 Marks)

b. Find out how many addresses are still available after these allocations.
(5 Marks)

Question Seven

(15 Marks)

If you want to find the local IP address assigned to your computer or the MAC address of your Ethernet Adapter, there is a quickest way to find this information and also you may perform other various network management tasks through windows IP commands. Write down a command which will enable you to:
(1.5 Marks Each)

a. Displays all available options.

b. Display output for ALL network connection adapters of the computer.

c. Drop the current IPv4 addresses which were assigned dynamically from a DHCP server.

d. Request new IPv4 addresses be dynamically assigned from a DHCP server.

e. Delete local DNS resolver cache of the computer.

f. Show the local DNS resolver cache entries.

g. Send the ICMP packets to specific IP address.

h. Find the path that a TCP/IP packet takes towards a destination target.

i. Show the established network TCP/IP connections of the local computer with remote hosts.

j. Displays all Address Resolution Protocol cache mappings.

END OF EXAMINATION PAPER

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